PLSclear requires an ISBN or ISSN number for all titles (unless the content is hosted on a website). If the title you are looking for does not have an ISBN/ISSN, please search for the title name in the first instance to see if it appears in the results.
If the content is hosted online, you can search for the top-level URL of the website. For example, search for PLSclear.com rather than PLSclear.com/publishers. Make sure not to include any hyphens or spaces in your URL.
If you cannot find it in PLSclear, you will need to refer your request to the publisher directly.